'Sports Anemia' Might Strike While The Athlete Is Hot

Many people exercise for health and an energy-boosting payoff. But if you feel like you're running on empty, you may be suffering from sports anemia.

Sports anemia is a term loosely applied to at least three different conditions: hemodilution, iron deficiency anemia and foot-strike anemia.

Technically, anemia is a condition in which you have a reduced amount of hemoglobin or a low number of red blood cells. The most common symptoms of this disorder are fatigue, weakness and, in extreme cases, shortness of breath or palpitations, or you may have no symptoms at all.

Hemoglobin is the substance inside red blood cells that transports oxygen from your lungs to the rest of your body. Your whole body, from bone to brain, runs on oxygen, and active muscles require huge amounts of it.

Normal hemodilution happens when the body adds water to the blood and increases the plasma, the fluid part of the blood. The amount of formed elements - erythrocytes (red blood cells), leukocytes (white blood cells) and platelets - stays the same.

A laboratory test shows less hemoglobin per unit of blood, but it doesn't note the overall increase in blood volume. Your blood has the normal amount of hemoglobin, but more plasma, so you have fewer red blood cells per unit of volume. Because the amount of hemoglobin remains constant, hemodilution isn't an anemic condition and has none of the symptoms of one.

According to Russell Pate, director of the Human Performance Laboratory at the University of South Carolina, an athlete has sports anemia when her hemoglobin concentration drops below 12 grams per deciliter. However, such levels of hemodilution may still be benign, he says. Pate's research suggests an athlete's performance could be affected by sports anemia, though results aren't conclusive.

The cause of this condition remains unknown. However, one reasonable explanation, favored by most researchers, holds that hemodilution is related to your body's cooling mechanism. When you exercise, your body dumps water onto your skin in the form of perspiration. Your blood brings fluid to the skin's surface through the capillaries: tiny, semipermeable vessels.

In order to sweat, you have to lose water from your blood. A great loss of fluid would cause your blood to become too concentrated and sticky to flow easily through the capillaries. Your body prevents that problem by storing extra water in the bloodstream.

Another condition known as sports anemia is iron deficiency anemia. Not exclusive to athletes, it occurs most often among women who may lose more iron each month when they menstruate than they take in. Your body's main use for iron is in making hemoglobin. Anemia caused by iron deficiency is relatively common, and a good physical exam should include a test for it.

Iron deficiency anemia develops in three stages, and you can live with a lack of iron without developing a true anemia. When your body is deprived of sufficient iron, it first begins to use iron stored in the liver, spleen and bone marrow to make hemoglobin. It then uses the iron that circulates in your blood serum. When these sources are depleted, your body stops making new hemoglobin.

Some symptoms may develop even in the early phases, when only storage iron levels are affected. Certain iron-containing enzymes needed for oxygen metabolism and myoglobin - an oxygen-storing substance in the muscles - suffer first. Women with inadequate storage iron don't process lactic acid efficiently and tire more quickly.

In the latter stages, your blood can't adequately carry oxygen from the lungs, and your oxygen transport system breaks down. At this point, you suffer aute anemic symptoms.

Some athletes experience a little-understood condition related to trauma. In runners, it's called foot-strike anemia. The trauma of the heel repeatedly striking the ground ruptures red blood cells. This rare condition is poorly defined. It may occur at the same time as other forms of sports anemia but is not directly related to them.

When these different anemic conditions interact, diagnosis is difficult and the type of treatment less apparent. For instance, a distance runner may have a harmless case of hemodilution, which requires no treatment, coupled with iron deficiency anemia. The only treatment for true anemia is iron supplementation, often with iron pills prescribed by a physician.

To prevent anemia or treat milder cases of iron deficiency, a modified diet with more foods high in iron is best. Most premenopausal women can eat red meat, the best source of nutritional iron, without fear of raising their cholesterol levels.

Those with high cholesterol levels, and non-meat eaters, can consume iron-fortified cereals and iron-rich foods like spinach, broccoli, beans, lentils and tomato juice. Some women need more concentrated doses of iron than their diets can provide. In these cases, a vitamin-mineral supplement is a good source of extra iron.